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Infinite loop in Keycloak SAML parser crashes the service

Priority LOW 34CWE-835Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-835.

Summary

Red Hat build of Keycloak 26.4 and 26.6 are affected by an infinite loop in the SAML 1.1 assertion parser, classified as CWE-835. The loop occurs when the parser handles an AuthorityBinding element within an authentication statement, following an incomplete fix for an earlier flaw. An unauthenticated remote attacker can make the parser consume all available memory, crashing the entire Keycloak service and making it unavailable to users.

Written with Claude Haiku 5.5 from the sources below · 2026-11-06

Description from the CNA

A flaw was found in the SAML 1.1 assertion parser of Keycloak, a tool used for identity and access management. The issue occurs when the parser handles a specific element called AuthorityBinding within an authentication statement. Due to an incomplete fix for a previous vulnerability, the parser can enter an infinite loop that consumes all available memory, causing the entire Keycloak service to crash and become unavailable to users.

Why it matters now

EPSS 0.00655 51st percentileScored 2026-11-07
Fix Fixed Red Hat: 4 advisories

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
Red HatRed Hat build of Keycloak 26.4—26.4.17-2Patch availableCNA
Red HatRed Hat build of Keycloak 26.4—26.4-29Patch availableCNA
Red HatRed Hat build of Keycloak 26.4—26.4-30Patch availableCNA
Red HatRed Hat build of Keycloak 26.4.17——Not affectedCNA
Red HatRed Hat build of Keycloak 26.6—26.6.8-2Patch availableCNA
Red HatRed Hat build of Keycloak 26.6—26.6-24Patch availableCNA
Red HatRed Hat build of Keycloak 26.6—26.6-24Patch availableCNA
Red HatRed Hat build of Keycloak 26.6.8——Not affectedCNA
Red HatRed Hat build of Keycloak 26.6.8——Not affectedCNA
Red HatRed Hat Single Sign-On 7——Not affectedCNA
  • Red Hat build of Keycloak 26.4 VendorRed Hat Affected — Fixed in 26.4.17-2 Patch available CNA
  • Red Hat build of Keycloak 26.4 VendorRed Hat Affected — Fixed in 26.4-29 Patch available CNA
  • Red Hat build of Keycloak 26.4 VendorRed Hat Affected — Fixed in 26.4-30 Patch available CNA
  • Red Hat build of Keycloak 26.4.17 VendorRed Hat Affected — Fixed in — Not affected CNA
  • Red Hat build of Keycloak 26.6 VendorRed Hat Affected — Fixed in 26.6.8-2 Patch available CNA
  • Red Hat build of Keycloak 26.6 VendorRed Hat Affected — Fixed in 26.6-24 Patch available CNA
  • Red Hat build of Keycloak 26.6 VendorRed Hat Affected — Fixed in 26.6-24 Patch available CNA
  • Red Hat build of Keycloak 26.6.8 VendorRed Hat Affected — Fixed in — Not affected CNA
  • Red Hat build of Keycloak 26.6.8 VendorRed Hat Affected — Fixed in — Not affected CNA
  • Red Hat Single Sign-On 7 VendorRed Hat Affected — Fixed in — Not affected CNA

CPE names CNA · 3

CPEVersionsRoleVendor
cpe:/a:redhat:build_keycloak:26.4::el926.4—Red Hat
cpe:/a:redhat:build_keycloak:26.6::el926.6—Red Hat
cpe:/a:redhat:red_hat_single_sign_on:77—Red Hat
  • cpe:/a:redhat:build_keycloak:26.4::el9 Versions 26.4 — ·Red Hat
  • cpe:/a:redhat:build_keycloak:26.6::el9 Versions 26.6 — ·Red Hat
  • cpe:/a:redhat:red_hat_single_sign_on:7 Versions 7 — ·Red Hat

Remediation

Upgrade Red Hat build of Keycloak 26.4 to 26.4.17-2, 26.4-29 or 26.4-30, and Red Hat build of Keycloak 26.6 to 26.6.8-2 or 26.6-24. Red Hat advisories RHSA-2026:95759, RHSA-2026:95760, RHSA-2026:95761 and RHSA-2026:95762 provide these fixes.

Written with Claude Haiku 5.5 from the sources below · 2026-11-06

Red Hat 4 advisories

  • RHSA-2026:95762 Released 2026-11-06 · Red Hat rating Important
    Red Hat build of Keycloak 26.6.8 Images Security Update
    • Red Hat build of Keycloak 26.6 rhbk/keycloak-operator-bundle, rhbk/keycloak-rhel9, rhbk/keycloak-rhel9-operator
  • RHSA-2026:95760 Released 2026-11-06 · Red Hat rating Important
    Red Hat build of Keycloak 26.4.17 Images Security Update
    • Red Hat build of Keycloak 26.4 rhbk/keycloak-operator-bundle, rhbk/keycloak-rhel9, rhbk/keycloak-rhel9-operator
  • RHSA-2026:95761 Released 2026-11-06 · Red Hat rating Important
    Red Hat build of Keycloak 26.6.8 Security Update
    • Red Hat build of Keycloak 26.6.8
Show 1 more Red Hat advisories
  • RHSA-2026:95759 Released 2026-11-06 · Red Hat rating Important
    Red Hat build of Keycloak 26.4.17 Security Update
    • Red Hat build of Keycloak 26.4.17

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat build of Keycloak 26.4Fixed RHSA-2026:95760
Red Hat build of Keycloak 26.4.17Fixed RHSA-2026:95759
Red Hat build of Keycloak 26.6Fixed RHSA-2026:95762
Red Hat build of Keycloak 26.6.8Fixed RHSA-2026:95761
Not affected: 1 product
  • Red Hat Single Sign-On 7

Timeline

  1. 2026-11-05 Threatist record created from CVE-2026-110931
  2. 2026-11-05 Alias added: GHSA-w9c8-6pxq-5xf8
  3. 2026-11-05 Affected versions changed · Red Hat
  4. 2026-11-05 CVSS score added · Red Hat
  5. 2026-11-06 Fix available: [email protected], [email protected], [email protected] · CNA
  6. 2026-11-06 2 new references · CNA
  7. 2026-11-06 Fix available: RHSA-2026:95761 · Red Hat
  8. 2026-11-06 Fix available: Red Hat build of Keycloak 26.6.8 · Red Hat
  9. 2026-11-06 Fix available: rhbk/[email protected], rhbk/[email protected], rhbk/[email protected] +3 · CNA
  10. 2026-11-06 2 new references · CNA
  11. 2026-11-06 Fix available: RHSA-2026:95760 · Red Hat
  12. 2026-11-06 Fix available: RHSA-2026:95762 · Red Hat
  13. 2026-11-06 Fix available: RHSA-2026:95759 · Red Hat
  14. 2026-11-06 Fix available: Red Hat build of Keycloak 26.4, Red Hat build of Keycloak 26.4.17, Red Hat build of Keycloak 26.6 · Red Hat
  15. 2026-11-07 EPSS moved to the 50th–90th percentile
  16. 2026-11-07 Priority changed: MEDIUM → LOW

References

  • TI-2019-15875 Protection mechanism failure in Jenkins Pipeline: Groovy Plugin KEVCVSS 3.1CRITICAL 9.9
  • TI-2019-15874 Protection mechanism failure in Jenkins Script Security Plugin KEVCVSS 3.1CRITICAL 9.9
  • TI-2019-08259 Underflow in PHP-FPM can lead to RCE KEVCVSS 3.1CRITICAL 9.8
  • TI-2019-05363 Code injection in Elastic Kibana KEVCVSS 3.1CRITICAL 10.0
  • TI-2019-03949 Out-of-bounds write in ESXi and Horizon DaaS KEVCVSS 3.1CRITICAL 9.8
  • TI-2018-16080 A code execution vulnerability exists in the Stapler web framework used by Jenkins 2.153… KEVCVSS 3.1CRITICAL 9.8
See all 7413 →

Sources